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United States Patent |
6,203,007
|
Choi
|
March 20, 2001
|
Paper discharging mechanism for an image processing apparatus
Abstract
A discharge mechanism capable of discharging a sheet facedown is
advantageous to miniaturization of a duplex printing apparatus. The
discharge mechanism includes a discharge roller gear engaged with a
driving gear; a pair of discharge rollers rotatable by the discharge
roller gear, keeping in contact with each other; a disklike support member
having a shaft fixed on a same line of a shaft of the driving gear,
intervening between the driving gear and the discharge rollers; a friction
disk attached to the discharge roller gear, for transferring a driving
force of the driving gear to the disklike support member; a compression
coil spring interposed between the friction disk and the disklike support
member, a shaft of a selected one of the discharge rollers passing through
the compressing coil spring; and a solenoid for restricting rotation of
the disklike support member when unactuated and for allowing rotation of
the disklike support member when supplied with a current. The disklike
support member has a pair of opposite stoppers formed at its outer
circumference. Each of the stoppers has two opposite protrusions, one of
which has a perpendicular outer wall, another of which has a slope.
Inventors:
|
Choi; Bong-Hwan (Suwon, KR)
|
Assignee:
|
Samsung Electronics Co., Ltd. (Suwon, KR)
|
Appl. No.:
|
212296 |
Filed:
|
December 16, 1998 |
Current U.S. Class: |
271/278; 271/184; 271/225; 271/291 |
Intern'l Class: |
B65H 029/00 |
Field of Search: |
271/186,291,8.1,225,287,184,303
|
References Cited
U.S. Patent Documents
4252309 | Feb., 1981 | Garrison et al. | 271/186.
|
4712785 | Dec., 1987 | Stemle | 271/187.
|
4890826 | Jan., 1990 | Rutishauser | 271/296.
|
5026036 | Jun., 1991 | Takahashi | 271/3.
|
5183249 | Feb., 1993 | Ichikawa | 271/186.
|
5537196 | Jul., 1996 | Matsumoto et al. | 355/320.
|
5549292 | Aug., 1996 | Plain | 271/291.
|
5692740 | Dec., 1997 | Holtje | 270/58.
|
Primary Examiner: Walsh; Donald P.
Assistant Examiner: Beauchaine; Mark J
Attorney, Agent or Firm: Bushnell, Esq.; Robert E.
Claims
What is claimed is:
1. A discharge mechanism in a duplex printing apparatus including a driving
gear, comprising:
a discharge roller gear engaged with the driving gear;
a pair of discharge rollers rotatable by the discharge roller gear, keeping
in contact with each other;
a disklike support member having a shaft fixed on a same line of a shaft of
the driving gear, intervening between the driving gear and the discharge
rollers;
a friction disk attached to the discharge roller gear, for transferring a
driving force of the driving gear to the disklike support member;
a compression coil spring interposed between the friction disk and the
disklike support member, a shaft of a selected one of the discharge
rollers passing through the compressing coil spring; and
a solenoid for restricting rotation of the disklike support member when
unactuated and for allowing the disklike member to rotate when supplied
with a current.
2. The discharge mechanism as claimed in claim 1, wherein said disklike
support member has a pair of opposite stoppers formed at its outer
circumference.
3. The discharge mechanism as claimed in claim 2, wherein each of said
stoppers has two opposite protrusions, one of which has a perpendicular
outer wall, another of which has a slope.
4. A discharge mechanism in a duplex apparatus, comprising:
a pair of discharge rollers forming a nip between them, each of said pair
of discharge rollers rotating about a shaft; and
a disklike support member attached to said shafts of said pair of discharge
rollers, each one of said pair of shafts intersecting said disklike
support member at separate points on said disklike support member at
opposite sides of a center point of said disklike support member, wherein
said disklike support member is capable of rotating, causing the shafts of
said discharge rollers to change positions, said disklike support member
rotating about said center point.
5. The discharge mechanism of claim 4, wherein said disklike support member
rotates 180 degrees about said center point for sheet inversion.
6. The discharge mechanism of claim 5, wherein said disklike support member
contains a pair of notches disposed on the outer circumference thereof 180
degrees apart, into which a lever is inserted to prevent further rotation
of said disklike support member.
7. The discharge mechanism of claim 6, further comprising:
a discharge roller gear disposed on the shaft of one of said pair of
discharge rollers; and
a driving gear that drives both said discharge roller gear and said
disklike support member.
8. The discharge mechanism of claim 7, wherein the axis of said driving
gear coincides with the axis and the center point of said disklike support
member and said nip formed between said pair of discharge rollers.
9. The discharge mechanism of claim 8, further comprising a solenoid for
controlling the rotation of said disklike support member by manipulating
said lever capable of being inserted into one of said pair of notches on
said disklike support member.
10. The discharge mechanism of claim 9, further comprising a friction disk
being attached to said discharge roller gear, for transferring a driving
force of the driving gear to the disklike support member.
11. The discharge mechanism of claim 10, further comprising a compression
coil spring interposed between said friction disk and the disklike support
member, said shaft of one of said pair of discharge rollers passing
through the compressing coil spring.
12. A method for discharging a duplex sheet of paper onto a discharge tray,
comprising the steps of:
providing a pair of discharge rollers each having a shaft and a disklike
support member, said pair of discharge rollers each attached to said
disklike support member at said shaft, said shaft of each of said
discharge rollers perpendicular to the surface of said disklike support
member, said pair of shafts intersecting said disklike support member at
separate points on said disklike support member, at opposite sides of a
center point of said disklike support member;
conveying said sheet between said pair of discharge rollers, the side last
printed on facing down;
halting the rotation of said pair of discharge rollers when said sheet is
almost entirely passed through said discharge rollers;
rotating said disklike support member 180 degrees, said discharge rollers
and said sheet being attached to said disklike support member;
initiating said pair of rotated discharge rollers to rotate in a reverse
direction; and
discharging said sheet of paper onto said discharge tray, said side last
printed on facing up.
13. The method of discharging a duplex sheet of claim 12, further
comprising:
providing a pair of notches disposed on the outer circumference of said
disklike support member, said pair of notches being 180 degrees apart from
one another;
providing a lever that can be locked into each one of said pair of notches;
disengaging said lever from one of said pair of notches;
rotating said disklike support member 180 degrees; and
engaging into place said lever into said other of said pair of notches.
14. The method of discharging a duplex sheet of claim 13, further
comprising:
activating a solenoid to disengage and engage said notches on said disklike
support member.
Description
CLAIM OF PRIORITY
This application makes reference to, incorporates the same herein, and
claims all benefits accruing under 35 U.S.C. .sctn.119 from an application
for DISCHARGE MECHANISM IN DUPLEX PRINTING APPARATUS earlier filed in the
Korean Industrial Property Office on Dec. 16, 1997 and there duly assigned
Ser. No. 69208/1997.
1. Field of the Invention
The present invention relates to an electrophotographic duplex printing
apparatus, and in particular, to a discharge mechanism for discharging
sheets facedown.
2. Description of the Related Art
Electrophotographic image forming apparatuses include an optical copier, a
digital copier, an LBP (Laser Beam Printer) and a facsimile. Among these
apparatuses, the LBP and the copier may have a duplex printing function.
An apparatus having the duplex printing function is called a duplex
printing apparatus. A user of the duplex printing apparatus can select one
of simplex and duplex printing modes at the discretion of the user.
Of concern is the ability of an apparatus to discharge duplex printed paper
so that the first side printed on comes out of the machine face down. This
may require a device for inverting a sheet of paper upon discharge. U.S.
Pat. No. 4,712,785 to Stemmle discloses one such mechanism. It is noted
that in Stemmle that a sheet diverter and two different paths are required
depending on if the device is to invert a sheet or not invert a sheet of
paper. U.S. Pat. No. 4,252,309 discloses a document flipper that
automatically flips or inverts a sheet of paper. However, such a device
does not allow for passage of a sheet of paper without inverting.
What is needed is a compact and simple device that can either invert a
sheet of paper or allow a sheet of paper to pass non-inverted.
The following patents each discloses the features in common with the
present invention: U.S. Pat. No. 5,026,036 to Takahashi, entitled Device
For Controlling Stacking Of Paper Sheets On An Intermediate Tray Of An
Image Forming Apparatus, U.S. Pat. No. 4,252,309 to Garrison et al.
entitled Document Sheet Flipper, U.S. Pat. No. 4,712,785 to Stemmle,
entitled Sheet Stacking Apparatus, U.S. Pat. No. 5,692,740 to Holtje,
entitled Disk Type Inverter-Stacker With Improved Sheet Control With
Automatically Repositionable Fingers, U.S. Pat. No. 5,183,249 to Ichikawa,
entitled Paper Conveyor, U.S. Pat. No. 5,549,292 to Plain, entitled Sheet
Stacking And Reversing Separator, U.S. Pat. No. 5,537,196 to Matsumoto, et
al. entitled Imaging Apparatus Equipped with Automatic Recirculating
Document Handler, and Sheet-Circulating Feeder.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a discharge
mechanism which is advantageous to miniaturization of a duplex printing
apparatus.
It is another object of the present invention to provide a discharge
mechanism capable of discharging a sheet with the side first printed on
facedown.
It is yet another object of the present invention to provide a device that
can allow a sheet of paper to pass uninverted or to invert a sheet of
paper upon passing.
It is still another object of the present invention to provide a discharge
mechanism enabling a duplex printing apparatus to match the order of pages
printed by an organic photoconductive drum with the order of print pages
provided from a computer.
To achieve the above object, a discharge mechanism in a duplex printing
apparatus having a driving gear includes a discharge roller gear engaged
with the driving gear; a pair of discharge rollers rotatable by the
discharge roller gear, the discharge rollers keeping in contact with each
other; a disklike support member having a shaft fixed on a same line of a
shaft of the driving gear, intervening between the driving gear and the
discharge rollers; a friction disk attached to the discharge roller gear,
for transferring a driving force of the driving gear to the disklike
support member; a compression coil spring interposed between the friction
disk and the disklike support member, a shaft of a selected one of the
discharge rollers passing through the compressing coil spring; and a
solenoid for restricting rotation of the disklike support member when
supplied with a current.
The disklike support member has a pair of opposite stoppers formed at outer
circumference. Each of the stoppers has two opposite protrusions, one of
which has a perpendicular outer wall, another of which has a slope.
BRIEF DESCRIPTION OF THE DRAWINGS
A more complete appreciation of the invention, and many of the attendant
advantages thereof, will be readily apparent as the same becomes better
understood by reference to the following detailed description when
considered in conjunction with the accompanying drawings in which like
reference symbols indicate the same or similar components, wherein:
FIG. 1 is a side view of a duplex printing apparatus with a known discharge
mechanism;
FIG. 2 is a side view of a duplex printing apparatus with a discharge
mechanism according to an embodiment of the present invention;
FIG. 3 is a front view of the discharge mechanism (50) of FIG. 2;
FIG. 4A is a side view of the discharge mechanism (50) of FIG. 2, for
explaining a state where the discharge mechanism operates in a simplex
printing mode; and
FIG. 4B is a side view of the discharge mechanism (50) of FIG. 2, for
explaining a state where the discharge mechanism operates in a duplex
printing mode.
DETAILED DESCRIPTION OF THE INVENTION
Referring to FIG. 1, the duplex printing apparatus has a simplex printing
mode and a duplex printing mode. In the simplex printing mode, an
uppermost sheet P in sheet cassette 110 or 112 is transferred to aligning
rollers 124 by a pickup roller 120 or 122 and undepicted fingers. As the
sheet whose leading end is aligned by the aligning rollers 124, passes
through a developing unit 130 and a fixing unit 140, a toner image is
printed on a front surface 2 of the sheet. The sheet is guided to a sheet
path 144 by a lever 143 and conveying rollers 142. Subsequently, the sheet
is discharged to a discharge tray 150 by conveying rollers 146 and
discharge rollers 148. Here, the sheet is delivered to the discharge tray
150 facedown. The sheet path guiding lever 143 is controlled by a
undepicted optical sensor, which may be positioned between the lever 143
and the conveying rollers 142 to detect a leading end of the sheet.
Further, it should be noted that the front surface (i.e., upper surface)
of the sheet is represented by reference numeral 2 and a back surface
(i.e., lower surface) of the sheet is represented by reference numeral 1.
In the duplex printing mode, the uppermost sheet P in one of the sheet
cassettes 110 and 112 is transferred to the aligning rollers 124 by the
associated pickup roller and the undepicted fingers. Thereafter, the upper
surface (i.e., front surface) 2 of the sheet is first printed while
passing through the developing unit 130 and the fixing unit 140. Here, the
sheet path guiding lever 143 moves up in response to a sheet detection
signal from the undepicted optical sensor, to guide the sheet to a sheet
path 145. Subsequently, the sheet passes through discharge rollers 152
until a rear end of the sheet is detected by an optical sensor which may
be positioned between a lever 154 and the discharge rollers 152. When the
rear end of the sheet is detected, the discharge rollers 152 rotate
reversely to forward the sheet to a sheet path 155. The sheet is again
transferred to the aligning rollers 124 by a plurality of conveying
rollers 160, 162, 164 and 166. Then, the lower surface (i.e., the back
surface) 1 of the sheet is printed while passing through the developing
unit 130 and the fixing unit 140. The sheet is guided to the sheet path
145 by the lever 143 and proceeds to the discharge rollers 152 until the
rear end of the sheet is detected. When the rear end of the sheet is
detected, the lever 154 blocks up the sheet path 155 and the discharge
rollers 152 rotate reversely to forward the sheet to a sheet path 149.
Finally, the sheet is discharged to the discharge tray 150 by discharge
rollers 148. Here, the upper surface 2 of the sheet is placed on the
discharge tray 150 facedown.
To increase an efficiency of a memory and reduce a printing time, the
duplex printing apparatus feeds the sheets in succession, prints them in
the page order of 1, 3, 2, 5, 4, 7, 6, 9 . . . , and stacks them on the
discharge tray 150 facedown. To this end, the printing apparatus includes
the sheet path 149 for reversing the sheet and the lever 154 separately,
which makes the apparatus complex in structure and large in size.
Therefore, the duplexing printing apparatus cannot match the order of
pages printed by an organic photoconductive (OPC) drum 130 in the
developing unit with the order of print pages provided from a computer,
resulting in extra software and hardware to keep tract of the page order.
Referring to FIG. 2, a duplex printing apparatus includes a discharge
mechanism 50 according to an embodiment of the present invention. The
discharge mechanism 50 is disposed in front of a discharge tray 51. The
discharge mechanism 50 is well illustrated in FIG. 3.
Referring to FIGS. 3 to 4B, the discharge mechanism 50 includes a pair of
discharge rollers 510a and 510b; a driving gear 520 engaged with a
discharge roller gear 512, for providing a driving force to the discharge
roller gear 512 of the discharge roller 510a; a disklike support member
501 fixed to a frame, intervening between the roller gear 512 and the
discharge rollers 510a and 510b, the disklike support member 501 having a
shaft fixed on the same line as a shaft of the driving gear 520; a
solenoid 70 for restricting rotation of the disklike support member 501
when unactuated and for allowing rotation of the disklike support member
when provided with a current; a friction disk 502 attached to one side of
the discharge roller gear 512; and a compression coil spring 503
intervening between the friction disk 502 and the disklike support member
501. Each discharge roller has one shaft 511. The shaft 511 of the
discharge roller 510a passes through the compression coil spring 503. The
respective elements of the discharge mechanism 50 are interlocked with one
another.
In operation, as the driving gear 520 rotates, the discharge roller gear
512 engaged with the driving gear 520 rotates the discharge roller 510a.
Here, the disklike support member 501 is normally restrained by an
actuator 72 of the solenoid 70 so that the disklike support member 501 is
unable to rotate. Accordingly, the discharge rollers 510a and 510b rotate
to discharge the sheet. In the meantime, when the solenoid 70 is provided
with a current in response to a sheet end detection signal from the
optical sensor (not shown) which is positioned between the lever 46 and
the discharge mechanism 50, the actuator 72 contacts the solenoid 70 so
that the disklike support member 501 is released from the solenoid 70.
Therefore, as the driving gear 520 rotates to discharge the sheet
facedown, the discharge roller gear 512 and the disklike support member
501 both rotate by the friction disk 502 and an elastic force of the
compression coil spring 503. Since the shaft of the driving gear 520 is
fixed to the frame and a shaft of the discharge roller gear 512 is not
fixed to the frame, the discharge roller gear 512 rolls about on the
driving gear 520. Here, the disklike support member 501 rotates by about
180.degree. and then, is restrained again by stoppers 5011 and 5012 formed
at the outer circumference thereof. Each of the stoppers 5011 and 5012 has
two opposite protrusions, one of which has a perpendicular outer wall,
another of which has a slope.
Referring back to FIG. 2, in a simplex printing mode, a uppermost sheet P
piled in one of sheet cassettes 10 and 12 is transferred to aligning
rollers 24 by a pickup roller 20 or 22 and undepicted fingers. As the
sheet whose leading end is aligned by the aligning rollers 24, passes
through a developing unit 30 and a fixing unit 40, a toner image is fixed
to a front surface (i.e., upper surface) 2 of the sheet by the heat and
pressure of a heat roller and a pressure roller. The sheet then proceeds
to the discharge mechanism 50 along a sheet path 44, being guided by a
sheet path guiding lever 46. Finally, the sheet is discharged to the
discharge tray 51 facedown by the discharge mechanism 50.
In a duplex printing mode, the discharge mechanism 50 operates in a
different way. The uppermost sheet piled in one of the sheet cassettes 10
and 12 is fed by the associated pickup roller and the undepicted fingers.
Subsequently, the fed sheet is aligned by the aligning rollers 24 and
passes through the developing unit 30 and the fixing unit 40, during which
the toner image is fixed to the upper surface (i.e., front surface) 2 of
the sheet by the heat and pressure of the heat roller and the pressure
roller. Thereafter, the sheet proceeds to the discharge mechanism 50 along
the sheet path 44 by the conveying rollers 42. In the meantime, when the
undepicted optical sensor disposed between the lever 46 and the discharge
mechanism 50 detects the rear end of the sheet, the discharge mechanism 50
rotates reversely and the lever 46 moves to close the sheet path 44 so
that the sheet may proceed along the sheet path 52. After the front
surface of the sheet is printed in this manner, the sheet proceeds to the
aligning rollers 24 again along sheet paths 54, 56 and 58 by conveying
rollers 60, 62, 64, 66 and 68. As the sheet passes again through the
developing unit 30 and the fixing unit 40, the toner image is printed on
the lower surface (i.e., back surface) 1 of the sheet, thereby completing
the duplex printing. After completion of duplex printing, the leading end
of the sheet reaches the discharge mechanism 50 along the sheet path 44.
Now, reference will be made to operation of the discharge mechanism 50 with
reference to FIGS. 4A and 4B. The discharge mechanism 50 is so designed as
to discharge the upper surface 2 of the sheet facedown.
FIG. 4A illustrates a state where the discharge mechanism 50 operates in
the simplex printing mode, wherein the disklike support member 501 is
restrained by the solenoid 70. Specifically, the stopper 5011 protruding
out from the outer circumference of the disklike support member 501 is
hooked by the actuator 72 of the solenoid 70 so that the disklike support
member 501 is unable to rotate. That is, as the driving gear 520 rotates,
the discharge roller gear 512 engaged with the driving gear 520 rotates
the discharge rollers 510a and 510b.
However, in the duplex printing mode, while the leading end of the sheet
reaches the discharge mechanism 50 and progresses between discharge
rollers 510a and 510b, if the optical sensor disposed between the lever 46
and the discharge mechanism 50 detects the rear end of the sheet, a
current is provided to the solenoid 70 so that the actuator 72 supported
by a tension coil spring 74 may move in the direction of arrow A and
contact the solenoid 70 to release the disklike support member 501.
Then, as illustrated in FIG. 4B, the disklike support member 501 rotates
counterclockwise (in an arrow direction) by the friction disk 502 and the
compression coil spring 503. The disklike support member 501 rotates by
about 180.degree. and stops again by the actuator 72 of the solenoid 70,
as the stopper 5012 is restrained by an end of the actuator 72. While the
disklike support member 501 rotates, the end of the actuator 72 makes
sliding contact with the outer circumference of the disklike support
member 501. When the disklike support member 501 stops rotating by the
actuator 72 of the solenoid 70, the discharge rollers 510a and 510b rotate
in a direction opposite to that of FIG. 4A to discharge the sheet to the
discharge tray 51 facedown.
It is preferable that at least two discharge mechanisms 50 are placed at
either side of the discharge tray 51. As can be appreciated from the
foregoing, the novel discharge mechanism contributes to miniaturization of
the duplex printing apparatus. Further, as compared with the conventional
one, the duplex printing apparatus with the novel discharge mechanism has
the total sheet path reduced in length, so that it is possible to print a
next page after completion of duplex printing for the present page.
Accordingly, the printing apparatus can print the sheets in the order of
the print pages provided from the computer, thereby increasing the
efficiency of the memory.
While the invention has been shown and described with reference to a
certain preferred embodiment thereof, it will be understood by those
skilled in the art that various changes in form and details may be made
therein without departing from the spirit and scope of the invention as
defined by the appended claims.
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